A computer simulation study on the mode conversion process from slow X-mode to fast X-mode by the tunneling effect

Katoh, Yutai; Iizima, M.

doi:10.1186/bf03352641

Cited by 8 publications

(6 citation statements)

References 7 publications

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“…There arises difficulty in theoretical treatments in a case that the spatial size of inhomogeneity is of the order of the wavelength of LO-mode waves, where the WKB approximation is invalid. The simulation studies have also pointed out that efficient LO-mode wave generation is expected in the case that the spatial scale of the density gradient is the order of wavelength (Katoh and Iizima, 2006;Kalaee et al, 2009). …”

Section: Introductionmentioning

confidence: 91%

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Simulation of mode conversion process from upper-hybrid waves to LO-mode waves in the vicinity of the plasmapause

et al. 2010

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Abstract. In order to clarify the role of the mode conversion process in the generation mechanism of LO-mode waves in the equatorial region of the plasmasphere, we have investigated the linear mode conversion process among upper-hybrid-resonance (UHR)-mode, Z-mode and LOmode waves by a numerical simulation solving Maxwell's equations and the equation of motion of a cold electron fluid. The wave coupling process occurring in the cold magnetized plasma are examined in detail. In order to give a realistic initial plasma condition in the numerical experiments, we use initial parameters inferred from observation data obtained around the generation region of LO-mode waves obtained by the Akebono satellite. A density gradient is estimated from the observed UHR frequency, and wave normal angles are estimated from the dispersion relation of cold plasma by comparing observed wave electric fields. Then, we perform numerical experiments of mode conversion processes using the density gradient of background plasma and the wave normal angle of incident upper hybrid mode waves determined from the observation results. We found that the characteristics of reproduced LO-mode waves in each simulation run are consistent with observations.

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Section: Introductionmentioning

confidence: 91%

“…We study the wave coupling process among UHR-mode, Z-mode and LO-mode waves by using a spatially twodimensional electron fluid model (Katoh, 2003;Katoh and Iizima, 2006;Kalaee et al, 2009). The basic equations are given as follows;…”

Section: Simulation Modelmentioning

confidence: 99%

Simulation of mode conversion process from upper-hybrid waves to LO-mode waves in the vicinity of the plasmapause

et al. 2010

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“…Under the WKB approximation, the difference in local plasma frequencies is described by the variation in the number density of the plasma medium in a spatial scale sufficiently larger than the spatial scale of wavelength. In the case that the spatial scale of the density gradient is the order of wavelength, however, we can expect efficient mode conversion due to the tunneling effect (Katoh and Iizima, 2006) even if the mismatch of the local plasma frequencies prevents the close coupling of plasma waves.…”

Section: Summary and Discussion Of Casementioning

confidence: 99%

“…Therefore, the width of the mismatch that develops between these branches and mode conversion can only take place by tunneling through the evanescent zone. Since the efficiency of the tunneling effect varies depending on the spatial scale of the density gradient (Katoh and Iizima, 2006), we change the width (L) of the inhomogeneous region to λ, 2λ, 4λ, or 8λ according to the wavelength of the incident waves. Here, we note that the spatial resolution used in our study is high enough to describe the propagation of plasma waves in the simulation system properly; as an example, one wavelength of incident UHR-mode waves is expressed by using over 45 grids in the case that the local plasma frequency is 2.0 e and the wave frequency is 2.03 e , with the wave normal angle of 65…”

Section: Summary and Discussion Of Casementioning

confidence: 99%

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Simulation of mode conversion from UHR-mode wave to LO-mode wave in an inhomogeneous plasma with different wave normal angles

et al. 2009

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We have investigated a linear mode conversion process among UHR-mode, Z-mode, and LO-mode waves by a computer simulation solving Maxwell's equations and the motion of a cold electron fluid. The characteristics of the wave coupling process occurring in the cold magnetized plasma were examined in detail for the case of an inhomogeneity of plasma density lying perpendicular to the ambient magnetic field. The dependence of the conversion efficiency on the incident wave normal angle, wave frequency, background plasma frequency, and steepness of density gradient was studied. The results show that an efficient mode conversion occurred in the conversion process from Z-mode to LO-mode waves rather than from the coupling between UHR-mode to LOmode waves. They also show that the highest conversion efficiency was obtained under the specific condition of the wave normal angle for the incident waves. In the specific case of such critical wave normal angles, we found that perpendicular components of refractive indexes became zero at the site of mode conversion, which is consistent with previously published results. We also show that the range of the critical normal angle varied depending on both the plasma frequency and the wave frequency. The simulation results also reveal that, when the steepness of the density gradient was taken into consideration, efficient mode conversion could be expected even in the case of the mismatch of the refractive indexes preventing the close coupling of plasma waves.

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High Performance Computing on Vector Systems 2008

Resch¹,

Roller²,

Benkert³

et al. 2009

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A computer simulation study on the mode conversion process from slow X-mode to fast X-mode by the tunneling effect

Cited by 8 publications

References 7 publications

Simulation of mode conversion process from upper-hybrid waves to LO-mode waves in the vicinity of the plasmapause

Simulation of mode conversion process from upper-hybrid waves to LO-mode waves in the vicinity of the plasmapause

Simulation of mode conversion from UHR-mode wave to LO-mode wave in an inhomogeneous plasma with different wave normal angles

High Performance Computing on Vector Systems 2008

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